Fuel quantity indicators, such as for use on aircraft, which determine the fuel quantity present in a fuel tank based on calculations of capacitance of a tank capacitor array and a compensation capacitor are well known in the art, such as disclosed in commonly owned U.S. Pat. Nos. 4,090,408 and 4,173,893, both of which name Geoffrey S. Hedrick, one of the inventors herein, as the sole inventor thereof. Each of the fuel quantity indicators disclosed in these patents are digital fuel quantity indicators and employ zero set adjustment. However, neither of these prior art systems is able to act as a universal fuel quantity indicator which can be reconfigured for a plurality of different fuel tank configurations such as by reprogramming the fuel quantity indicator constants to conform to varing fuel tank parameters associated with different aircraft or different fuel tank configurations on a given aircraft. This has required that several different fuel gauges be inventoried for a given aircraft and for a given aircraft manufacturer. This is so despite the fact that digital fuel quantity indicators employing a programmable read only memory as an integral part of the fuel gauge are known in the prior art, such as disclosed in U.S. Pat. No. 4,083,248 in which the programmable read only memory is used to compensate for errors in the probe for a specific tank. However, this system does not reconfigure the fuel quantity indicator and is tank dependent as opposed to being tank independent and, moreover, is not an alterable data source of different groups of parameters specific to a plurality of changing fuel tank configurations. This is also so despite the prior art use of a read only memory as a look up table in a digital fuel gauge for transforming the measured signal into an output signal proportional to the amount of fuel in the tank, such as disclosed in U.S. Pat. No. 4,487,066 which, once again, is not a universal fuel gage which may be reconfigured for different fuel tank configurations. Thus, none of the prior art known to applicants, provides a universal fuel gage which may be reconfigured to a plurality of different fuel tank configurations, such as by changing the stored parameters specfic to a given fuel tank configuration which determine the measuring factors for the calculated fuel quantity determination so as to set up the initial conditions for a given fuel tank for a universal fuel quantity indicator, nor such an arrangement in which a removably connectable interface is employed for a universal fuel gauge which, in conjunction with the fuel quantity indicator, can provide an auxiliary data source which is reprogrammable by the user to the particular specific fuel tank configuration with which the universal fuel quantity indicator is being used at that time. These disadvantages of the prior art are overcome by the present invention.